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It's been discussed a millions time so what's a million and 1 more

Jeepercreeper01

NAXJA Forum User
Location
Arizona
I own a 2001 jeep cherokee xj. I recently dropped a reman motor with no miles into it.also replaced the water pump with a hi-flow, thermostat (195°), thermo housing, electric fan, temp sensor, radiator cap and fan clutch. Radiator is approximately 3 years old from cfs 2 row. It's not leaking.
Here is my issue. The damn thing is running at 215 down the highway. I live in AZ where it's 108 degrees today. Is this normal or should it be running a little cooler.
Things to note : the Ac is currently out of operation. So it hasn't been in use while driving. Also, the radiator was burped and filled with %100 antifreeze. No distilled water.
What would cause it to run so hot?? :banghead:
 
The 100% antifreeze actually doesn't cool as well as pure water.
A 50-50 mix will cool it down some. I'd try that and go from
there...
 
Are you sure the engine is overheating?
Buy or borrow an digital infrared thermometer and check the temperature of the thermostat housing, when the engine is hot, and see how the actual temp compares with the indicated temp on the dash gauge.
 
108 ambient is pretty dang hot

But yes you need to get an IR temperature gun and verify gauge against the actual temperature. You can also use an OBDII scanner to read the sensor value and verify the gauge is showing actual value.
 
I really appreciate all the input guys. The Jeep is overheated on me since day one when I purchased it 10 years ago. I thought replacing a whole new motor and a lot of cooling components would be a cure-all. I have both these items you mentioned a hook up my scanner today and bust out the infrared temp gun and compared against the actual gate itself. My only other thought is that the radiator being 3 to 4 years of age is plugged up
 
I suspect part of the problem is the high concentration of antifreeze, that can damage a motor with overheat! dilute to 50/50 mix using distilled water. tapwater has too many minerals in it, so buy the distilled at any grocery store. you want distilled, not the purified nor spring water. Distilled is what to use..
 
One other thing to try, is install a 180* thermostat.

I'll catch flak for suggesting that, but a lower temp
thermostat won't affect closed loop operation at all,
and will give you a lower underhood temperature.
 
I haven't tried them, but some people install the hood vents.
Sounds like they have success.


I'm going to try a bottle of waterwetter coolant additive for this summer.
My entire coolant system is rebuilt....main fan is stock with new clutch tho.
If 90 degrees here in Missouri, my stock guage reads above the 210 hash mark.
 
A properly operating cooling system should be able to handle it. In the upper nineties last couple of weeks I still get 195 on the dash, even in stop and go driving. Haven't done highway hill climbing but I did last summer with temps around 101 and still was under 200.
 
my 2c, double check that there is no air in the system.

The late model cooling system(closed) is "self purging" so that's not necessary as long as you keep the reservoir full and a good cap on it.
 
Aside from proper ratio, I also use watter wetter in my cooling system.
 
X2 on a proper coolant mix. With 108 ambient, I'd go 50-70% at most. Pure antifreeze is about 35% less effective than a 50/50 mix. Automatic transmission? Is the torque converter locking up properly? That'll add some heat via the tranny cooler in the radiator.
 
I live in Az.
Here's what I did and I run at 170 always.
Remove the thermostat.
That is all.
You can thank me once you do it.
 
before the trolls arrive.
last summer I was averaging 220ish anytime I stopped moving.
I replaced the fan clutch
got an upgraded water pump.
replaced the rad.
replaced the electric fan.
replaced all hoses.
coolant flush after flush.
nothing solved it.
now at the end of summer I put the Tstat back in. and when it gets hot in AZ I remove it.
temps over 100 degrees and jeeps just struggle.
 
before the trolls arrive.
last summer I was averaging 220ish anytime I stopped moving.
I replaced the fan clutch
got an upgraded water pump.
replaced the rad.
replaced the electric fan.
replaced all hoses.
coolant flush after flush.
nothing solved it.
now at the end of summer I put the Tstat back in. and when it gets hot in AZ I remove it.
temps over 100 degrees and jeeps just struggle.


That's certainly A solution, but something else is wrong there. Clogged heater core, something in the block, wrong coolant mix. I can't be 100% sure but I had trouble at 104 on hills at 80 mph for a couple years before a remaned engine swap for other reasons, and I did the HD radiator at the same time, and even with old hoses it seems to be almost impossible to get this anywhere out of 195-200 in all conditions now including Texas summers. XJs just aren't that different otherwise so physics dictates something else is going on.



I'm genuinely curious. I do have a manual, so I'm not cooling my transmission through the radiator, maybe that makes enough of a difference right on the edges.
 
I understand why XJs have issues with heat, engine bay doesn't breath, exhaust manifold placement, too small of a radiator etc. I don't like running at or over 200* at all. I have a newer rebuilt motor also with a new radiator. So My plan is to run a180* stat with a burp hole drilled in it, new housing and temp sensor with a bypass cut in the gasket, eliminate the clutch fan and go s-blade efan on the passenger side which I've adapted to a new stock fan shroud and a newer stock replacement fan on the driver side. I'll run a 180* stat inline on the heater hose for the pass Efan and my other fan is already on a switch. Hopefully this will keep it 190* or cooler. Air trapped in the coolant system seems to be a problem with the Xj.
 
...... run a180* stat with a burp hole drilled in it..........Air trapped in the coolant system seems to be a problem with the Xj.
I also drill a relief hole in the thermostat using a 1/8" drill bit. I think this helps to release trapped air.
 
The current mopar thermostat has a little wobble valve in it, coolant forces it closed but air can escape

Mopar_52028186AC.sized.jpg
 
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